Purpose for blowdown ; ...
Published by Amitabha Majumdar
Purpose for blowdown ; Under normal operating condition the only reason for blowdown is to lower the suspended and dissolved solids content of the boiler water. These solids are brought in by the and since the steam leaving the boiler is relatively pure concentration of solids will develop in the boiler water. Excessive amount of suspended solids will cause deposition of sludge .Excessive amount of dissolved solids have the same deleterious effect as suspended solid. In fact , in many cases the effect of boiler water solids on steam purity needed no longer be considered of in controlling boiler water balance. BLOWDOWN CONTROL: It is important that blowdown is such that the boiler water concentration . At the same time it is equally important that excessive blow down to be avoided because of the related heat loss. Regardless of the factor limiting the boiler water blowdown is usually based on the determination of total solids content of the boiler water. especially a boiler operating pressure above 600 psig blow down is based on the limiting value of silica contents and for boiler operating pressure 400 psig silica con. is not a problem. (for further details BETZ HAND BOOK OF INDUSTRIAL WATER CONDIIONING (sixth edition)